The specific objective for this Phase I proposal is to generate, by recombinant DNA technology, a polypeptide having the primary sequence of human interleukin 7: a. construction of the synthetic gene coding for human interleukin 7 with a E. coli condon bias, and cloning of the synthetic gene into a plasmid to verify that the sequence is correct as planned, and b. cloning of the verified structural gene fragment into an expression vector to check for the expression level of the desired protein.